RAHUL DOSHI DISCUSSED THE IMPORTANCE OF CREATING AESTHETIC AND FUNCTIONAL TRANSITIONAL RESTORATIONS
The purpose of this article is to outline a simple system to achieve a functional occlusion and a predictable aesthetic rehabilitation with porcelain veneer techniques. It follows the fundamentals of smile design, tooth morphology, form and function.
Creating beautiful temporaries is one of the best ways of having satisfied patients who will grow your practice by referring more people.
The team approach
The combination of knowledge and artistic skills of the dentist and the close interaction with the ceramist technician provides a predictable end result. The dentist’s role is to understand the needs of the patient and formulate a plan that includes not only aesthetic considerations, but occlusal, periodontal and functional requirements.
The principles of smile design
In developing anterior restorations, specifically veneers and crowns, the dentist must determine the following important factors:
- The position of the incisal edge in the ‘rest position’ of the lips. This is determined by the age of the patient and whether they are male or female
- The width/length ratio of the central incisors should be 75-80%
- The colour of the required restorations and the colour of the existing dentition/restorations; thus determining the thickness of the restoration, necessary tooth reduction and the choice of feldspathic or pressed porcelains
- The size of teeth using The Golden Proportion rule: an anterior photograph (a two dimensional image) should produce the width ratio between central incisor: lateral incisor: canine of 1.6: 1: 0.6
- The size and position of the centre line should be vertical, not canted, and ideally in the midline
- The arch-form needs to be assessed for lingual or labial version of the teeth in comparison to the ideal curved arch-form
- The position of contact points and the position of the incisal embrasure areas progressively graduate cervically from the anterior to the posterior teeth
- The size of embrasure areas progressively increase from the anterior to the posterior
- The axial alignment of teeth should converge to the midline at an angle of 5°.
This highlights the importance of understanding the correct amount of tooth visible with ‘lips at rest’ when determining the new incisal edge position for designing the perfect smile.
Transitional restorations testing space closure and change in bucco-lingual inclination of anterior teeth.
It is within this framework that the entire smile is developed. The best place to determine these variables is within the patient’s mouth. The dentist’s knowledge of smile design and the patient’s guidance through functional movements and speech will dictate the final position and appearance of the incisors.
Transitional restorations showing change in perceived Golden Proportion and width/length ratio of teeth by changing the position of the reflective line angles.
After receiving the impressions, the ceramist will pour two sets of models using a high-quality die stone (Diekeen Ivory). The first set is used for diagnosis and will be untouched as a ‘before’ model.
The second set is the working model for carrying out trial preparations and then diagnostic wax-ups, to establish the position, size and shape of teeth in the ideal arch-form, with the correct anterior and canine guidance.
Once the diagnostic wax-up is completed and approved, a matrix can be fabricated with Sil-Tech putty. The matrix is used to fabricate the provisional restorations in the clinical session.
- After tooth preparation, the teeth are cleaned with Chlorhexadine Gluconate (Consepsis, Ultradent Products Inc) and rinsed with water
- All prepared teeth are spot etched in the middle third of the facial surface for 15-20 seconds and thereafter washed thoroughly
- Multiple layers of a desensitising agent such as Gluma is placed on the teeth, and gently air dried
- A thin layer of partially filled resin (e.g. Optibond 2FL) is placed on the teeth. A primer or single component bonding system should not be used as the temporaries will be difficult to remove
- Each tooth is cured for 20 seconds with an LED light or a conventional halogen light
- The matrix is then filled with Luxatemp, placing the syringe tip deep within the matrix to avoid air bubbles. The matrix is seated on the teeth, then removed after three minutes
- Any gross excess material is trimmed with a bur before re-contouring, finishing and polishing
- LuxaFlow can also be used to repair or add on to the temporaries. These areas can be micro-etched or roughened with a bur and a bonding agent applied. However, our experience shows that these additional steps are not practically necessary
- Finishing burs are used to finalise the marginal aspects (being careful not to disturb the tissue or alter the final preparations)
- Time is taken to accurately adjust the provisional restorations for an ‘ideal smile’ and correct occlusal form
- The final lustre is created with Luxaglaze Glaze and Bond. This is painted onto the temporary restorations, air-dried and light-cured.
A functional and aesthetic preview to a new smile
Fabrication of the final restorations should begin only after the occlusion has been checked, the provisional restorations are accepted to be comfortable and stable and the patient is happy with the smile design.
This typically requires the provisional to be in place for a few days in order to obtain family approval and suggestions as well as confirm phonetic control.
A visit is arranged for the patient to come and have a review of the trial smile.
Valuable feedback can be gained by asking the following questions:
- What do you like about your new provisional smile?
- What do you dislike about your provisional smile?
- What other changes would you like us to make for your definitive smile?
- Please give us a rating out of 10 on how pleased you are with the provisional smile.
- Are you happy with the shade? Would you like us to make the final shade the same, darker or lighter?
- Are you happy with the surface texture and smoothness?
- Do you prefer the right-hand side or the left-hand side of your new smile?
- Are you happy with the length of the front teeth?
These questions really allow the practitioner to understand the patient’s aesthetic wants of their new smile.
Further simple changes can be made to the provisional’s as appropriate; after gaining these important viewpoints from the patient.
This is done by further re-contouring the Luxatemp and/or adding LuxaFlow in specific areas, so the patient can have another preview and confirm acceptance of the trial smile.
The following records are taken at this visit to communicate to the ceramist the approved form and shape of the provisional restorations including a confirmation of the patient’s desire of the shade:
- An accurate silicone impression of the temporaries
- Further digital photographs of the patient’s smile
- Precise lengths of the six anterior teeth using a Jeneric
- Pentron ‘T’ ruler (with an accuracy of up to 0.1mm)
- A check bite record of the provisional restorations and the opposing arch using Luxabite (DMG) (if the occlusion is challenging)
- A stick bite of the transitional restorations
Temporisation is an integral part of comprehensive treatment involving smile design concepts. It represents the treatment phase that allows a dentist to be an artist.
Temporary fabrication also provides proper communication for the laboratory, which directly affects the case.
Eliminating as much of the guesswork as possible helps create a predictable result, and a happy smiling patient.